* I2C: Don't get stuck, if pullups are missing (timeout error)

[avrcpm.git] / avr / i2c.asm

diff --git a/avr/i2c.asm b/avr/i2c.asm
index 493217303ecab863d9498b1e72d1212f4924b5e4..0d96ace594a04d2f64464c2241a148e1f488f9ba 100644 (file)
--- a/avr/i2c.asm
+++ b/avr/i2c.asm
@@ -74,7 +74,15 @@
 ; 
 ; wait ready:
 ;       (1<<TWIE)|(1<<TWSTO)
-; 
+;
+;----------------------------------------------------------------------
+;
+;i2c_result    <  0    Error. 
+;                      -1 general/unknown error
+;                      -2 time out 
+;              >= 0    No error
+;                      > 0 status tbd.
+;
 ;----------------------------------------------------------------------
 
        .dseg
@@ -112,7 +120,6 @@ i2c_buf:
        ldd     temp2,z+oi2ci_idx                       
 
        inm8    temp,TWSR
-
        cpi     temp,TWI_START
        breq    i2ci_START
        cpi     temp,TWI_REP_START
@@ -135,19 +142,19 @@ i2ci_REP_START:
 i2ci_MTX_ADR_ACK:
 i2ci_MTX_DATA_ACK:
        ldd     temp,z+oi2c_bufcnt
-       cp      temp2,temp                              
-       brsh    i2ci_12
+       cp      temp2,temp                              ;all bytes tranmited?
+       brsh    i2ci_12                                 ; yes
        add     zl,temp2
        adc     zh,_0
        inc     temp2
-       ldd     temp,z+oi2c_buf
+       ldd     temp,z+oi2c_buf                         ;next byte
        outm8   TWDR,temp
        ldi     temp,(1<<TWEN)|(1<<TWIE)|(1<<TWINT)
        rjmp    i2ci_end
 
 i2ci_12:
-       std     z+oi2c_result,_255
-       rjmp    i2ci_default
+       std     z+oi2c_result,_0                        ;done
+       rjmp    i2ci_default                            ;stop transceiver
 
 i2ci_MRX_DATA_ACK:
        add     zl,temp2
@@ -167,7 +174,7 @@ i2ci_32:
        rjmp    i2ci_end
 
 i2ci_MRX_DATA_NACK:
-       std     z+oi2c_result,_255                      ;result = 1
+       std     z+oi2c_result,_0                        ;result = ok
        add     zl,temp2
        adc     zh,_0
        inm8    temp,TWDR
@@ -194,22 +201,30 @@ i2c_init:
        ldi     temp,I2C_BR
        outm8   TWBR,temp
        outm8   TWDR,_255                       ;
-       ldi     temp,(1<<TWEN)                  ;Enable TWI, disable Interupts.
+       ldi     temp,(1<<TWEN)                  ;Enable TWI, disable TWI interrupt.
        outm8   TWCR,temp
 
-       ldi     temp,1
-       sts     i2c_result,temp
+       sts     i2c_result,_0
        ret
 
 ;------------------------------------------------------------------
 
 i2c_waitready:
-       push    temp
-i2c_b:
+
+       ldi     temp,30
+       sts     delay_timer1,temp
+i2c_wrl:
        inm8    temp,TWCR
        andi    temp,(1<<TWIE)|(1<<TWSTO)
-       brne    i2c_b
-       pop     temp
+       breq    i2c_wre
+       lds     temp,delay_timer1
+       tst     temp
+       brne    i2c_wrl
+
+       ldi     temp,-2
+       sts     i2c_result,temp
+i2c_wre:
+       tst     temp
        ret
 
 ;------------------------------------------------------------------
@@ -220,25 +235,16 @@ i2c_b:
 ;
 
 i2c_write:
-       rcall   i2c_waitready
 
+       rcall   i2c_waitready
+       brmi    i2c_we
        push    zh
        push    zl
        push    xh
        push    xl
 
-#if 0
-       rcall   printstr
-       .db     '\r', 'W', 0,0
-       mov     temp,temp2
-       rcall   printhex
-       rcall   printstr
-       .db     ": ", 0,0
-       rcall   dbg_hexdump_line
-#endif
-
        ldiw    x,i2c_result
-       st      x+,_0                           ;result = 0
+       st      x+,_255                         ;result = not ok
        st      x+,temp2                        ;store size
        ld      temp,z+
        cbr     temp,0x01
@@ -257,6 +263,7 @@ i2c_wle:
        pop     xh
        pop     zl
        pop     zh
+i2c_we:
        ret
 
 
@@ -269,14 +276,16 @@ i2c_wle:
 ;      temp:   return (fail = 0, else succsess)
 
 i2c_read:
+
        rcall   i2c_waitready
+       brmi    i2c_re
 
        push    zh
        push    zl
        push    xh
        push    xl
        ldiw    x,i2c_result
-       st      x+,_0                           ;result = 0
+       st      x+,_255                         ;result = not ok
        st      x+,temp2                        ;store size
        ld      temp,z
        sbr     temp,0x01
@@ -288,18 +297,9 @@ i2c_read:
 
        rcall   i2c_waitready
 
-#if 0
-       rcall   printstr
-       .db     '\r', 'R', 0,0
-       mov     temp,temp2
-       rcall   printhex
-       rcall   printstr
-       .db     ": ", 0,0
-#endif
-
        lds     temp,i2c_result
-       tst     temp
-       breq    i2c_ex                          ;
+       sbrc    temp,7
+       rjmp    i2c_ex                          ;
 i2c_rl:
        ld      temp,x+
        st      z+,temp
@@ -307,14 +307,12 @@ i2c_rl:
        brne    i2c_rl
 
 i2c_ex:
-       lds     temp,i2c_result
        pop     xl
        pop     xh
        pop     zl
        pop     zh
-#if 0
-       rcall   dbg_hexdump_line
-#endif
+i2c_re:
+       lds     temp,i2c_result
        ret
 
 ;------------------------------------------------------------------
@@ -331,7 +329,7 @@ vi2c_addr:
        .cseg
 
 vi2c_stat_get:
-       lds     temp,vi2c_stat
+       lds     temp,i2c_result
        ret
 
 vi2c_param_get:
@@ -356,10 +354,12 @@ vi2c_param_set:
 ;
 
 vi2c_read:
+
        rcall   i2c_waitready
+       brmi    vi2c_rex
 
        ldiw    z,i2c_var
-       std     z+oi2c_result,_0                ;result = 0
+       std     z+oi2c_result,_255              ;result = not ok
        lds     temp3,vi2c_blen
        std     z+oi2c_bufcnt,temp3             ;store size
        adiw    z,oi2c_buf
@@ -376,15 +376,15 @@ vi2c_read:
        rcall   i2c_waitready
 
        lds     temp,i2c_result
-       tst     temp
-       breq    vi2c_ex                         ;
+       sbrc    temp,7
+       rjmp    vi2c_rex                                ;
 vi2c_rl:
        ld      temp,z+
        lcall   dram_write_pp
        dec     temp3
        brne    vi2c_rl
 
-vi2c_ex:
+vi2c_rex:
        ret
 
 ;------------------------------------------------------------------
@@ -395,9 +395,11 @@ vi2c_ex:
 ;
 
 vi2c_write:
+
        rcall   i2c_waitready
+       brmi    vi2c_wex
        ldiw    z,i2c_var
-       std     z+oi2c_result,_0                ;result = 0
+       std     z+oi2c_result,_255              ;result = not ok
        lds     temp3,vi2c_blen
        std     z+oi2c_bufcnt,temp3             ;store size
        adiw    z,oi2c_buf
@@ -414,27 +416,23 @@ vi2c_wle:
        ; Enable TWI, TWI int and initiate start condition
        ldi     temp,(1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWSTA)
        outm8   TWCR,temp
-
+vi2c_wex:
        ret
 
+;------------------------------------------------------------------
+
 
 vi2c_ctrl:
        cpi     temp,1
        brne    vi2c_c1
-       rcall   vi2c_read
-       rjmp    vi2c_ce0
+       rjmp    vi2c_read
+
 vi2c_c1:
        cpi     temp,2
-       breq    vi2c_c2
-       ldi     temp,0xff
-       rjmp    vi2c_ce
+       brne    vi2c_c2
+       rjmp    vi2c_write
 vi2c_c2:
-       rcall   vi2c_write
-vi2c_ce0:
-       lds     temp,i2c_result
-       com     temp
 vi2c_ce:
-       sts     vi2c_stat,temp
        ret
 
 ;------------------------------------------------------------------